全文获取类型
收费全文 | 683篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 58篇 |
综合类 | 3篇 |
化学工业 | 205篇 |
金属工艺 | 9篇 |
机械仪表 | 15篇 |
建筑科学 | 30篇 |
能源动力 | 36篇 |
轻工业 | 60篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 43篇 |
一般工业技术 | 102篇 |
冶金工业 | 54篇 |
原子能技术 | 27篇 |
自动化技术 | 61篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 18篇 |
2020年 | 3篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 20篇 |
2014年 | 22篇 |
2013年 | 63篇 |
2012年 | 25篇 |
2011年 | 45篇 |
2010年 | 39篇 |
2009年 | 33篇 |
2008年 | 33篇 |
2007年 | 31篇 |
2006年 | 22篇 |
2005年 | 28篇 |
2004年 | 23篇 |
2003年 | 21篇 |
2002年 | 17篇 |
2001年 | 5篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 21篇 |
1997年 | 22篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1968年 | 2篇 |
排序方式: 共有707条查询结果,搜索用时 0 毫秒
51.
Junichi Koseki Hong Kimhor Susumu Nakajima Sarju Mulmi Kenji Watanabe Masaru Tateyama 《Soils and Foundations》2010,50(5):747-755
In order to investigate the seismic behavior of conventional type and geosynthetic-reinforced soil retaining walls, 1-g model shaking tests were conducted. Model walls having a height of about 50 cm were placed on a subsoil layer and backfilled with a layer of dense dry Toyoura sand. They were subjected to several steps of horizontal irregular excitations. As a result, generation of negative pore air pressure in the backfill was observed. The maximum amplitude of the negative pore air pressure during each shaking step increased with the base acceleration. Based on analyses of the measured data, it was inferred that such negative pore air pressure was caused by outward wall displacement relative to the backfill and not by dilative behavior of the backfill. It would cause a reduction in the seismic earth pressures exerted from the backfill. This feature suggests an advantage of a rigid full-height facing for reinforced soil walls over the segmental types of facing. A simplified numerical procedure to evaluate earth pressure was applied while considering the effects of the negative pore air pressure, and it could qualitatively simulate the measured behavior in terms of the seismic earth pressure and the angle of failure plane in the backfill. 相似文献
52.
53.
Takeda K Ishiguro Y Tanaka R Maruyama J Kasamatsu T Okawa S Hori S 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2002,43(5):280-288
Ion-trap GC/MS/MS was evaluated for the multi-residue determination of pesticides in agricultural products. Matrices were extracted from samples (spinach, carrot, onion and brown rice) with acetone and submitted to gel permeation chromatography, followed by a clean-up step through a graphite carbon cartridge. Thirty-five pesticides were added to either matrix, and analyzed by GC/MS/MS. Detection limits of pesticides by GC/MS/MS was almost the same as those by GC/MS (SIM). Coefficients of variation of peak area in 5 measurements of each pesticide at 0.1 microgram/mL or 0.05 microgram/mL with or without matrices were mostly acceptable, though those of 20 pesticides out of 35 were higher than 10% at a concentration of 0.02 microgram/mL. It was indicated that matrix artifacts, which interfere with GC/MS-Scan analysis, could be eliminated in some cases by using GC/MS/MS. 相似文献
54.
Nosal Briana M. Sakaki Junichi R. Kim Dae-Ok Chun Ock K. 《Food science and biotechnology》2022,31(8):1081-1088
Food Science and Biotechnology - Although coffee has been reported as a major contributor to antioxidants in the diet, there are limited studies assessing how brewing methods and types of coffee... 相似文献
55.
Although EDTA-dependent pseudothrombocytopenia (EDTA-PTCP) is of practical importance because failure to recognize this clinical entity may result in misdiagnosis and subsequent mismanagement of the patients, the pathophysiological nature of EDTA-PTCP remains unknown. To develop an effective way to evaluate the platelet counts in patients with EDTA-PTCP, we introduced aminoglycosides-supplemented anticoagulating agents. When kanamycin was pre-supplemented with EDTA for anticoagulating blood samples from EDTA-PTCP patients there was no significant change in the platelet counts and the morphology of blood cells after 150 min of incubation at room temperature. Furthermore, when kanamycin was added to EDTA-anticoagulated blood samples from EDTA-PTCP patients within 30 min after blood withdrawal, rapid dissociation of platelets without apparent morphological changes of blood cells was observed, and complete blood cell counts as well as the histogram patterns were almost the same as those examined immediately after blood sampling. The dissociation of aggregated platelets was also detected when other antibiotics were used, although it was associated with some extent of morphological changes of blood cells. These findings indicate that the supplementation of aminoglycosides either before or after blood sampling is a useful method for the diagnosis EDTA-PTCP and for the evaluation of platelet counts in patients with EDTA-PTCP. 相似文献
56.
Mikinori Hotta Junichi HojoKatsutoshi Komeya Junichi TatamiTakeshi Meguro Hirohisa MasudaKenji Morinaga Yi-Bing Cheng 《Materials Letters》2011,65(1):116-118
Ca-α SiAlON powders were prepared by carbothermal reduction-nitridation of CaO-Al2O3-SiO2 glasses at 1450 °C for 2 h in nitrogen. The content of Ca-α SiAlON phase was 65-81% in the products, and the other phases were AlN and β-SiAlON. The products contained hollow spheres with the size of around 5 μm in diameter. The particle morphology was almost identical to that of Ca-α SiAlON prepared from CaCO3-Al2O3-SiO2 powder mixtures. 相似文献
57.
Previous papers have shown ΔKRP to be a useful parameter describing fatigue crack propagation behavior, where ΔKRP is an effective stress intensity factor range corresponding to the excess RPG load (re-tensile plastic zone's generated load) in which the retensile plastic zone appears under the loading process. In this paper, the relationship between ΔKRP and the zone size (
) (which is smaller between the tensile plastic zone at maximum load and the compressive plastic zone at minimum load) was investigated using a crack opening/closing simulation model so as to consider a physical meaning of ΔKRP. As a result, it becomes clear that ΔKRP dominates the zone size
where fatigue damage mostly occurs. This result supports the following crack propagation equationwhere C and m are material constants.Simulation and fatigue crack propagation tests were then carried out for compact tension (CT), center cracked tension (CCT) and four points bend (4PB) specimens under constant amplitude loading to obtain C and m values for HT-50 steel. Fatigue crack propagation tests were also carried out under constant amplitude loading using CCT specimens with residual stress distribution due to flame gas heating at the center line or edge lines. The T specimen introduced tensile residual stress at the tip of a notch, and the C specimen introduced compressive residual stress. It therefore becomes clear that tensile residual stress leads to a decrease in RPG load, while compressive residual stress leads to increase in RPG load, and that the simulation results are in good agreement with the experimental RPG load. It also becomes clear that simulated crack growth curve using the simulated
and the above equation is in good agreement with the experimental curve. It is understood that tensile residual stress creates only a slight increase in crack propagation rate and compressive residual stress create a big decrease a crack propagation rate. 相似文献
58.
Hydrogels that contain phosphate groups in side chains were studied for their usefulness in drug‐delivery soft contact lenses (SCLs). Naphazoline, a model drug having a cationic group, was incorporated into an SCL because of its phosphate groups and was released over a period of about 14 h. For the SCL, the naphazoline content was equivalent to the phosphate group content. It is suggested that drug‐delivery SCLs can be designed to contain the needed amount of a drug through the choice of the ionic group for the ligand. Furthermore, the SCL having amide groups and phosphate groups had high transparency and an unchanged shape. It is suggested that amide groups and phosphate groups must be introduced into the polymer in equimolar amounts to give the necessary polymer–drug interaction. Therefore, hydrogels having a drug‐delivery system were synthesized by the inclusion of a phosphate group and an amide group. These hydrogels are also applicable to SCL materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 731–735, 2005 相似文献
59.
T Ando T Yoshikawa T Tanigawa M Kohno N Yoshida M Kondo 《Canadian Metallurgical Quarterly》1997,61(19):1953-1959
The mechanism of the generation and the quantitative analysis of singlet oxygen (1O2) formed by the exposure of a hematoporphyrin derivative (HpD) to light was re-evaluated by electron spin resonance (ESR) combined with 2,2,6,6,-tetramethyl-4-piperidine (TMPD). The change from TMPD to 2,2,6,6,-tetramethyl-4-piperidine-N-oxide (TAN) has been reported to depend on singlet oxygen. However, we confirmed that this reagent also react with superoxide anion (O2-) and hydroxyl radicals (OH). Therefore, the reactions between TMPD and 1O2, O2- and OH were re-examined using a kinetic approach. We found that the generation of TAN was proportional to the concentration of TMPD and HpD, as well as to the duration and strength of the illumination. The generation of TAN was not inhibited by dimethyl-sulfoxide (DMSO) or superoxide dismutase (SOD). The reaction rate between TMPD and 1O2 was determined to be 5.0 x 10(-7) M min-1. The generation of 1O2 from HpD was 2.7 x 10(-7) M min-1 under our conditions. The competitive reaction observed between 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and TMPD for O2- or OH shows that TMPD reacts with both forms of active oxygen, but gave no ESR signal. The second-order reaction rate constant of TMPD between O2- and OH was calculated as 73 M-1 s-1 and 1.5 x 10(9) M-1 s-1, respectively. The photochemical generation of 1O2 from methylene blue, another sensitizer, was also demonstrated by this method. These results show that ESR signal of TAN can be used for the highly selective monitoring of 1O2. 相似文献
60.
Unique Features of Mobile Commerce 总被引:1,自引:0,他引:1
While the market potentials and impacts of web-based e-commerce are still in the ascendant, the advances in wireless technologies and mobile networks have brought about a new business opportunity and research attention, what is termed mobile commerce. Commonly, mobile commerce is considered to be another new application of existing web-based e-commerce onto wireless networks, but as an independent business area, mobile commerce has its own advantages and challenges as opposed to traditional e-commerce applications. This paper focuses on exploring the unique features of mobile commerce as compared with traditional e-commerce. Also, there are still some limitations arisen in m-commerce in contrast to web-based e-commerce. Finally, current state of mobile commerce in Japan is presented in brief, with an introduction of several cases involving mobile commerce applications in today's marketplace. 相似文献